Wheel offset and backspace measure the same thing but in a little different way. They tell you where in the wheel well a particular wheel will sit.
Offset is a measurement in millimeters from the backside of the mounting plate to the center line of the wheel. A positive number puts the mounting plate further away from the backside of the rim. A negative measurement moves it closer to the backside. Since offset is based on the center line, the width does factor in. That is to say an 8-inch wide +45mm offset and 7-inch wide +45mm offset results in a 1/2" difference in wheel positioning. The 8-inch wide will be further into the wheel well. To gain a better understanding of the offset of a wheel, read our tech article on this topic.
Backspace measures the distance from the mounting plate to the back edge of the wheel. The higher the backspace the further into the fender well it will sit.
Confusing? It can be. The good news is Tire Rack takes care of all the guesswork for you. When you shop by vehicle, we'll show you options that fit your vehicle. In some instances, there may be a fitment note explaining any potential issues, but in most cases no modifications are needed.